Temporal and spatial changes in the distribution of heaths within the city of Toruń according to analysis of cartographic and remote-sensing materials, and field exploration

Abstract

The paper describes changes in the distribution and the surface area of heaths during the last, nearly 120 years at two research sites located in the city of Toruń. The first site "JAR" is a former land of military manoeuvres in the northern part of the city, where a unit of the Soviet Army had been stationed after the 2nd World War till 1991. The second site "Glinki", situated at the south-western end of the city, was also exploited as a military land. During the 2nd World War, a German prisoner-of-war camp was located here, and after the war some industrial plants were built and allotment gardens were established, whereas part of the area was treated as a wasteland. The history of both areas and the vegetation changes were reconstructed from the series of temporal topographic maps and aerial photos, as well as a high-resolution Ikonos satellite image. The aforementioned source materials were analysed with the technology of Geographical Information Systems, applying the software Arc-GIS ArcView 9.3. For both sites, the range was determined, as well as the number of patches with common heather and the total area of heaths in particular years of land cover and land use mapping. The present state of heaths was defined based on the direct field exploration carried out with the use of GPS navigational devices. It was found that at present 22 heather patches occur at the site JAR, with the total area of11.7328 ha. Within the Glinki district, also 22 heather patches occur with the total area of 3.5701 ha. And thus, these are the largest sites of heaths located within the administrative boundaries of Toruń. Data collected through the field exploration of the site JAR were superimposed on the spatial development plan of the future housing estate. At an intersection of both information layers, fragments of the area were outlined where heaths can be preserved after the construction of a housing estate is completed. Their area is small. In the area of the Glinki district, the rate of expansion of industrial areas was determined for the last several years, as well as future changes in the land use were discussed, which will arise due to a housing estate scheduled for building here. The aforementioned analyses enabled to evaluate the present developmental state of both research areas, as well as to determine the future of low shrub communities, which occur here and which constitute a type of an ecological system listed among the UE protected habitats. The obtained results increase our knowledge on heaths in Toruń, and at the same time - also in Poland and in Europe.